1. Field of the Invention
Water baths are used to detect leaking glass, plastic or metal aerosol containers and or valves after they have been filled with a product and pressurized with a propellant. Such testing is necessary to comply with Department of Transportation (D.O.T.) regulation No. 173.306 Part 3, Section V.
A water bath, as it exists on today's market, consists of a tank filled with water at approximately 120.degree. - 140.degree. F.
Through the water and the length of the tank, a conveyor carries an aerosol container from the input end to the discharge. The container is conventionally carried on the conveyor by means of a puck or nest which must be fitted to the size of the particular containers to be tested.
Different size containers require different sets of pucks at a cost of from $1,000 to $1,500 per set dependent upon size, quantity required, length and speed of conveyor.
An operator is required to carefully insert part of the container into the puck at the intake end and another operator required to take the container out of the puck at the discharge end.
The container, passing through the hot water of the tank, increases the pressure of the propellant, and should be a "leaker" due to a defective valve, crimp or container, bubbles will appear in the water.
An inspector, checking for "leakers", will then remove the rejected container.
2. Description of the Prior Art
The following U.S. patents illustrate various prior art conveyor belt designs which have in the past been available for testing sundry types of containers water immersion:
RUBIN 699,244 CUSHMAN, ET AL 1,446,161 DAVIS 3,270,552 MUCCI 3,350,919 AQVIST 3,495,444 GUNDAL, ET AL 3,550,432
Rubin discloses a machine for testing cans which have been charged with compressed air. The cans are passed into a hot water bath and potentially leaky cans can be noted by the passage of bubbles through the water. Rubin furthermore teaches a system for automatically discriminating between leaky and good cans. The actual means for holding the can in place is an axial compression clamping means, requiring flat ends on both sides of the container.
Cushman teaches a bottling and testing apparatus for commonly bottled beverages, such as soft drinks, wherein only one size of bottles may be placed upon angle-shaped strips of metal arranged in pairs and riveted to a moving belt. This machine is not adjustable; adapted for only one size bottle.
Davis teaches an apparatus for testing pressurized receptacles in a heated liquid bath, and employs magnets to hold containers below water; thusly, limited to ferro-magnetic containers. Together with the magnets, the patentee employs nonadjustable guide rails.
Mucci teaches another testing apparatus disclosed for pressurized aerosol cans. However, the clamp means for holding the container below the top of the heated liquid bath, as seen in FIGS. 8 and 9, requires an arm 100 pressurized against the side of the aerosol wall by means of spring 109. Upright struts 89 are required on opposite side walls of the aerosol container to further hold the container in place. Consequently, several limiting factors are involved in the use of such arrangement. The mounting, including rollers 108 and upright pegs 111, limit clockwise movement of the lever so that cans of unusually large or small diameters cannot be employed by using such a device. Futhermore, when cans of very large or very small heights are employed, spacers 94, 95 must be replaced. Additionally, only one can be mounted at a given point on the conveyor, whereas the dual mounting of the instant invention allows an equivalent total belt length one half the length of any single mounting.
Aqvist teaches another testing means for aerosol cans, however, his entire structure depends upon whether cans float or sink in a heated liquid bath; categorically not relying upon bubble production from cans suspended from a belt.
While Gundal teaches a testing apparatus employing heated water to raise the pressure inside the package to a point in which leaking bubbles will be produced, the cans are held below a water level surface by pumping water through conduits having holes in communication with the bottom of the containers. Rapid water pumping causes a reduction in pressure below the level of the can, thus holding the can in place. Gundal, et al does not employ any suspension clamping means whatsoever; both requiring the expenditure of a large quantity of energy in pumping the water through the conduits in order to keep the cans in place, and being adaptable only for flat bottomed cans.
None of the above noted references teach a combination which even categorically and advantageously employs a suspended aerosol clamping means, as is taught by the instant invention.
Other workers have in the past employed means to suspend containers for water bath testing, however, none have employed the particularly advantageous combination of elements as is taught hereinafter for the instant invention. The following patents are also illustrative of prior art clamping devices; as well as certain other subcombination features which are per se well known in the field of the instant invention:
Netherlands 6,700,897 NORTON 287,048 MONROE 358,562 MANN 369,539 JOHNSON 876,558 YOUNGS 2,292,983 DAVIDSON 3,848,459
The Netherlands patent shows a device employing a cammed arrangement of gripping cans, in the neck region just below a cap. However, as seen from FIGS. 4 and 5, the clamp is not universally adaptable to various neck diameters; requiring further a plunger mechanism to come down over the holder assembly so as to open it for both connection and release of the can. As a result, a different clamp and plunger actuator assembly is also required for each different can size to be tested.
The patents to Norton, Mann and Monroe illustrate water baths using different types of steam coils for heating. Norton also shows a drying trough, at M, where the source of heat is another steam coil. Norton also teaches yet another type of cradle and compression clamping arrangement, at FIG. 7, which must be physically adjusted every time a different can size is used. Monroe illustrates using an additional steam pipe at 24 to clean the cans as they travel along a conveyor. Mann shows, at FIG. 5 a spring loaded chute for releasing a can which is conventionally held on a conveyor by axial compression, as shown at FIG. 4.
Johnson similarly and conventionally illustrates holding cans to be tested shown with a compression device at FIG. 1. The non-analogous patent to Youngs shows a device for testing rubber articles, and is of present interest only for showing a conveyor employing hangers on either side of a belt, and for a further showing that a water bath may conventionally employ a wetting agent.
Finally, Davidson illustrates yet another known device for testing aerosol cans that is without structural similarity to the particularly advantageous structure of the instant invention.